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J Dawson

Publications and source records attributed to J Dawson.

At least 109 records · Page 6Linked to original sources
PubMed1995

The effects of fasting on the thermogenic, metabolic and cardiovascular responses to infused adrenaline.

The effects of fasting on the thermogenic, lipolytic and cardiovascular responses to adrenaline were examined in nine normal, young, non-obese subjects. Each subject attended for study after 12, 36 and 72 h fasting. After basal measurements adrenaline was infused at 25 ng/min per kg ideal body weight for 90 min. Fasting increased the thermogenic effect of the adrenaline (mean 14.6 (SE 1.7), 16.6 (SE 1.8), 22.6 (SE 1.6) J/min per kg fat-free mass after 12, 36 and 72 h fasting respectively; P < 0.001, ANOVA). Basal plasma palmitate turnover increased with duration of fasting (1.48 (SE 0.22), 1.95 (SE 0.34) and 2.26 (SE 0.33) mumol/min per kg body weight; P < 0.001, ANOVA), but the response to adrenaline was unaffected by fasting. The percentage values for basal plasma palmitate turnover oxidized were 44 (SE 2; 12 h), 46 (SE 5; 36 h) and 42 (SE 4)% (72 h). In response to adrenaline this percentage fell, suggesting that adrenaline infusion may favour intra-tissue lipid oxidation.

Adult↗
PubMed1995

Isolated muscle atrophy of the distal upper extremity in cervical spinal cord compressive disorders.

The purpose of this article is to clarify one mechanism of muscular atrophy of the distal upper extremity that we attribute to cervical compression (Hirayama-type amyotrophy) by medical imaging and anatomical studies of the cervical spine. Five young male patients (mean age: 22.6 years) with this disorder showed characteristic findings to include an abnormal anterior displacement of the posterior dura wall in flexion that resulted in an anteroposterior compression of the spinal cord segment from C7 to C8. To identify an anatomical relationship to this disorder, the lower cervical spine was studied using 11 embalmed adult human cadavers. Abundant posterior epidural ligaments were observed between the posterior dura mater and the ligamentum flavum. Posterior epidural ligaments in the cervical spine have not been reported previously. The anterior displacement of the dura mater may be attributed to a lack of and/or insufficiency of the posterior epidural ligaments.

Adolescent↗
PubMed1995

Conversion from 2.5 mg to 1.25 mg indapamide in patients with mild to moderate hypertension.

BACKGROUND: Indapamide is an effective antihypertensive drug with diuretic and vasodilating activities. The common starting dose has been 2.5 mg to 5 mg. A lower dose formulation (1.25 mg) is now available. The safety and efficacy of switching patients from indapamide 2.5 mg to indapamide 1.25 mg was evaluated in this randomized, double-blind, multicenter clinical trial. METHODS: Three hundred seventy-eight adult patients with mild to moderate essential hypertension were enrolled in a washout period, during which patients received single-blind placebo for 4 weeks. All 378 patients qualified for the study and received open-label treatment with indapamide 2.5 mg for 8 weeks. Of the 378 patients, 265 responded to indapamide 2.5 mg and were randomized to receive double-blind treatment with either indapamide 1.25 mg (n = 132) or 2.5 mg (n = 133) for 8 weeks. Overall, 245 of the 378 patients who were initially enrolled completed the study. The primary efficacy variable was the number of patients in each treatment group who maintained a supine diastolic blood pressure of < or = 90 mm Hg (treatment success) by the end of the double-blind period (week 16). RESULTS: Treatment with indapamide 1.25 mg once daily was as efficacious as the 2.5-mg once-daily dose. No significant difference was observed for the percentage of patients who achieved treatment success between the patients switched from indapamide 2.5 to 1.25 mg (74%) and the control group maintained on indapamide 2.5 mg (70%). The incidence of drug-related adverse events during the double-blind period was similar between the two treatment groups. The mean change from pretreatment baseline to endpoint in serum potassium was -0.2 mEq/L (-0.2 mmol/L) in the indapamide 1.25 mg treatment group, compared with -0.4 mEq/L (-0.4 mmol/L) in the indapamide 2.5 mg treatment group. CONCLUSIONS: Indapamide 1.25 mg given once daily for 8 weeks was as effective as 2.5 mg once daily in reducing systolic and diastolic blood pressure in patients with mild to moderate hypertension.

Adult↗
PubMed1994

Comprehensive quality management program for radiation oncology.

A quality management program for both external beam irradiation (electron and photon modes) and brachytherapy (high dose rate (HDR) and low dose rate (LDR) has been developed. The program follows current USA federal regulations for therapeutic administration of by-product materials. After implementation of the program, 54 HDR patients, 36 LDR brachytherapy patients and 311 external beam patients (including 30 stereotactic radiosurgery cases) were treated. The results of this program are presented.

Brachytherapy↗
PubMed1994

Prevention of rebleeding from oesophageal varices: two-year follow up of a prospective controlled trial of propranolol in addition to sclerotherapy.

A prospective randomised trial comparing propranolol and sclerotherapy to sclerotherapy alone was conducted over a 2-year follow up in a district hospital setting of unselected patients. Rebleeding and survival were analysed. Thirty-nine patients were randomised to propranolol plus sclerotherapy and 34 to sclerotherapy alone. The two groups were clinically comparable. There was no significant difference in the cumulative percent of patients free of rebleeding; 54% of the sclerotherapy group rebled compared to 52% of the group treated with propranolol plus sclerotherapy (Hazard ratio 1.09 (0.54-2.22) and p = 0.81, NS). Two-year actuarial survival was also not significantly different, with 77% of the propanolol plus sclerotherapy group surviving, compared to 74% of sclerotherapy alone (Hazard ratio 1.08 (0.35-2.22) and p = 0.79, NS). The mean time to eradication of varices was not significantly different between the two groups (propranolol plus sclerotherapy 222 days, sclerotherapy alone 243 days), nor did the rate of variceal recurrence differ (72.7 vs 72 days). This study did not show long-term improvement in rebleeding or survival using propranolol in addition to a regular sclerotherapy programme.

Adolescent↗
PubMed1994

Effects of fasting on fatty acid kinetics and on the cardiovascular, thermogenic and metabolic responses to the glucose clamp.

1. The effects of fasting for 12, 36 and 72 h were examined in 19 normal subjects. Each subject was studied before and during a euglycaemic (4 mmol/l) hyperinsulinaemic (100 m-units min-1 m-2) clamp. Measurements were made of palmitate turnover and oxidation, glucose disposal, thermogenesis, intermediary metabolites and cardiovascular variables. 2. Basal respiratory exchange ratio fell from 0.78 +/- 0.01 to 0.75 +/- 0.01 to 0.72 +/- 0.01 with fasting (P < 0.001). In response to the clamp it rose to 0.91 +/- 0.02, 0.83 +/- 0.01 and 0.77 +/- 0.01 after 12, 36 and 72h respectively. Metabolic rate rose during the clamp by 0.41 +/- 0.06, 0.11 +/- 0.03 and 0.14 +/- 0.04 kJ/min respectively (P < 0.001 for 36- and 72-h values versus that at 12h). 3. Fasting reduced total insulin-mediated glucose disposal rates from 42.6 +/- 2.5, to 31.0 +/- 1.8 to 21.3 +/- 1.5 mumol min-1 kg-1 body weight after 12, 36 and 72h respectively (P < 0.001). Glucose oxidation fell from 16.9 +/- 1.1 to 8.7 +/- 1.7 to 0.2 +/- 1.3 mumol min-1 kg-1 body weight over the same period (P < 0.001). Non-oxidative glucose disposal rates did not change significantly. 4. Basal plasma palmitate turnover increased with duration of fasting, being 1.16 +/- 0.08, 1.72 +/- 0.17 and 2.30 +/- 0.35 mumol min-1 kg-1 body weight. In response to the clamp, palmitate turnover fell to 0.42 +/- 0.05, 0.69 +/- 0.08 and 1.28 +/- 0.45 mumol min-1 kg-1 body weight. Plasma palmitate oxidation was 0.58 +/- 0.04, 0.75 +/- 0.06 and 1.13 +/- 0.11 mumol min-1 kg-1 body weight basally, and fell to 0.16 +/- 0.02, 0.28 +/- 0.04 and 0.43 +/- 0.13 mumol min-1 kg-1 body weight by the end of the clamp. The proportion of total lipid oxidation represented by plasma non-essential fatty acid oxidation was not affected by fasting, but fell in response to the clamp. 5. Fasting caused a progressive resistance to the effects of insulin and glucose on oxidative glucose disposal and on forearm glucose uptake. Insulin-mediated glucose storage was unaffected by fasting, but the apparent cost of this storage was reduced by fasting.

Adult↗
PubMed1994

Regular partners and risky behaviour: why do gay men have unprotected intercourse?

Studies in both the UK and the USA continue to show that gay and bisexual men put themselves at risk of exposure to HIV through unprotected intercourse, most often with regular partners. As part of a larger study of homosexually active men, 310 men who had had unprotected anal intercourse with a man in the previous year were asked to describe the last occasion on which this had happened. The majority of men had had unprotected intercourse with a regular partner and did not perceived it as risky, although most did not know the HIV status of their partner. Regular and non-regular partners were perceived differently. Men were more likely to be emotionally involved in regular partners and to perceive unprotected penetrative sex with a regular partner as not risky. Future health education initiatives must take into account men's emotional involvement in regular partners and their perception of unprotected intercourse with such partners as not risky.

Adolescent↗
PubMed1994

Regional heterogeneity of function in hypertrophic cardiomyopathy.

BACKGROUND: In patients with hypertrophic cardiomyopathy (HCM), left ventricular ejection performance may be normal while segmental myocardial function is distinctly abnormal. The advent of magnetic resonance tissue tagging has allowed the noninvasive evaluation of intramyocardial segmental shortening in vivo in a topographic and temporal manner. METHODS AND RESULTS: Ten patients with HCM documented by echocardiography and 10 healthy volunteers were studied with magnetic resonance tissue tagging by spatial modulation of magnetization. Percent circumferential myocardial shortening (%S) was compared at endocardium, midwall, and epicardial levels at four regions around the left ventricular short axis and from four short axis slices from apex to base at four or five time intervals during systole. In 8 patients and 8 control subjects, longitudinal shortening was evaluated within the septum and the lateral free wall at three levels from apex to base. Circumferential %S was less in HCM patients than in control subjects in the septal (13 +/- 5% versus 24 +/- 6%, P = .0002), inferior (13 +/- 5% versus 21 +/- 4%, P = .001), and anterior (17 +/- 5% versus 21 +/- 3%, P < .03) regions but not in the lateral region. Circumferential end-systolic %S was reduced in patients with HCM compared with control subjects at all levels from apex to base. The normal transmural gradient in circumferential end-systolic shortening was preserved with greatest %S at the endocardium. Most of the total cumulative circumferential shortening occurred earlier in systole in patients compared with control subjects, especially within the septum. Longitudinal end-systolic %S was depressed throughout the septum in patients compared with control subjects, most markedly at the base, but was normal in the lateral free wall. CONCLUSIONS: Circumferential myocardial segment shortening is depressed in HCM in the septum, inferior, and anterior regions and at all levels from apex to base, and much of the total cumulative shortening occurs early in systole. Longitudinal shortening is reduced in the basal septum in HCM. The heterogeneity of regional function in these patients may reflect the regional variation in the myocardial disarray and fibrosis that is characteristic of this disorder.

Adolescent↗
PubMed1994

A comparison of the thermogenic, metabolic and haemodynamic responses to infused adrenaline in lean and obese subjects.

The objective of this work was to study adrenoceptor sensitivity in vivo in a number of tissues in lean and obese humans. The thermogenic, metabolic and cardiovascular responses to a 90 min infusion of adrenaline were measured. The subjects were eleven obese subjects (Body Mass Index 36.0 +/- 1.2 kg/m2) and 10 non-obese subjects (Body Mass Index 21.9 +/- 0.7 kg/m2). Metabolic rate, heart rate, blood pressure, forearm blood flow, plasma palmitate turnover and oxidation were measured. Thermogenic responses to adrenaline were similar in the lean and obese groups (14.4 +/- 1.6 and 15.1 +/- 1.6 J/min/kg fat free mass respectively). Of the cardiovascular variables measured, only the increase in forearm blood flow during adrenaline infusion differed between lean and obese, being 3.9 +/- 0.5 and 1.9 +/- 0.3 ml/min/100 ml forearm respectively. Basal plasma palmitate turnover rates were lower in the obese when expressed per unit fat mass (2.32 +/- 0.17 and 7.61 +/- 1.20 mumol/min/kg fat mass respectively). Basal plasma palmitate oxidation rates were higher in the obese when expressed per unit fat free mass (1.53 +/- 0.19 and 0.82 +/- 0.12 mumol/min/kg fat free mass respectively). In response to adrenaline palmitate turnover increased similarly in both groups, but plasma palmitate oxidation rates fell in the obese whilst they were unchanged in the lean. In the basal state the obese do not appear to have a defect in fat oxidation, but their response to infused adrenaline may favour fat storage over oxidation. No thermogenic defect was shown in the obese.

Adult↗
PubMed1994

Perceptions of general practice among homosexual men.

BACKGROUND: Primary care has an important role to play in the prevention and management of the human immunodeficiency virus (HIV). It has been suggested that homosexual men experience a variety of problems in relation to primary care. AIM: As part of a larger study, it was decided to examine the extent to which a sample of homosexually active men experienced difficulties in general practice and whether they consulted their general practitioner for problems related to HIV or the acquired immune deficiency syndrome (AIDS). METHOD: Homosexual men were recruited for interview in 1991-92 from a variety of sources including genitourinary clinics and homosexual organizations. RESULTS: Of 623 men registered with a general practitioner 44% had not informed their general practitioner of their sexual orientation and 44% of the 77 men who were HIV antibody positive, as confirmed by the study, had not informed their general practitioner of this fact. Men who viewed their practice as unsympathetic towards homosexual men were less likely to have informed their general practitioner of their sexual orientation or HIV status. The majority of men (87%) nevertheless viewed primary care as an appropriate source of HIV/AIDS advice. CONCLUSION: There is considerable scope for improvement in the acceptability of general practice to homosexual men.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Uptake of acetaminophen (paracetamol) by isolated rat liver cells.

The characteristics of the uptake of acetaminophen (N-acetyl-p-aminophenol or paracetamol, APAP) in incubations of isolated rat liver cells were consistent with diffusion of the drug being the predominant mechanism of APAP influx in these cells at concentrations above 0.5 mM. At lower substrate concentrations (below 0.5 mM) a saturable component was apparent. Both uptake processes could have a role in the control of the metabolism of APAP, because, at low concentrations, there was no intracellular accumulation of unconjugated drug, all the APAP entering the cell being converted to sulphate and glucuronide. After addition of drug, there was a lag phase of approximately 5 min before APAP-glucuronide and APAP-sulphate appeared in the incubation medium; during this time both conjugates accumulated inside the cells. These results have implications for our understanding of the mechanisms of APAP transport, and indicate how these processes may affect the drug's overall metabolism.

Acetaminophen↗
PubMed1993

Nosocomial pneumonia during stress ulcer prophylaxis with cimetidine and sucralfate.

BACKGROUND: Recent studies have questioned the use of histamine (H2) receptor antagonist in stress ulcer prophylaxis because of an increased incidence of nosocomial pneumonia and subsequent death. DESIGN: This prospective randomized study compared prophylaxis with cimetidine vs sucralfate. SETTING: Medical/surgical intensive care unit in Springfield, Mass. PATIENTS: One hundred fourteen patients were enrolled. INTERVENTIONS: Cimetidine, administered as a primed continuous infusion using a 300-mg bolus followed by 37.5 mg/h, was compared with sucralfate, administered via nasogastric tube, at a dosage of 1 g every 6 hours suspended in 20 mL of sterile water. MAIN OUTCOME MEASURES: End points of the study included nosocomial pneumonia, gastrointestinal hemorrhage, and death. RESULTS: Fifty-six patients were randomized to receive cimetidine and their rate of pneumonia was 12.5%; upper gastrointestinal hemorrhage, 3.6%; and mortality, 33.9%. Fifty-eight patients were given sucralfate, and their rate of pneumonia was 13.8%; upper gastrointestinal hemorrhage, 3.4%; and mortality, 37.9%. There were no significant differences between these study end points. In patients who had pneumonia, 80% of isolates were aerobic gram-negative bacilli. CONCLUSIONS: These observations suggest that the rate of nosocomial pneumonia is not increased in patients in the intensive care unit who receive prophylaxis with cimetidine to prevent stress ulcer bleeding.

Administration, Oral↗
PubMed1993

Conventional versus laparoscopic surgery for acute appendicitis.

A total of 155 consecutive patients with suspected acute appendicitis were studied to compare laparoscopic and conventional operations. Patients were not randomized: laparoscopy was performed when a suitably trained surgeon and laparoscopic instruments were available. Laparoscopic appendicectomy was attempted in 51 patients and was successful in 46 (90 per cent); all conversions to open operation were because of marked inflammatory adhesions around the appendix. There were no intraoperative complications. Reintroduction of normal diet and discharge from hospital occurred earlier after laparoscopic than open surgery (P < 0.05). The requirement for analgesia after successful laparoscopic surgery was less than that after conventional appendicectomy, but the difference was not significant. The incidence of wound infection was reduced after the laparoscopic procedure (P = 0.06). It is concluded that laparoscopic appendicectomy is practical and may have advantages over conventional operation, although a randomized study is necessary.

Acute Disease↗
PubMed1993

Interleukin-1 (IL-1) production in a mouse tissue chamber model of inflammation. I. Development and initial characterisation of the model.

A simple and reliable animal model to quantify interleukin-1 (IL-1) production at a site of inflammation has been developed and characterised. This model involves the subcutaneous implantation of sterile Teflon chambers (30 mm x 10 mm diameter) into the backs of mice. After 14 days, a straw coloured transudate fluid was present in the lumen of the implanted chamber which was withdrawn for the determination of baseline measurements of various inflammatory parameters. A localised chronic inflammatory response was then induced in the chambers by injection of 1% zymosan or Bordetella pertussis vaccine (BPV) (in presensitised animals). The local inflammatory reaction in the chamber, over a 30 day time course, was characterised by leucocyte infiltration, and marked increases in protein, prostaglandin E2, IL-1 and IL-6 concentrations in the chamber fluid. A rapid increase in plasma concentrations of the acute-phase reactant serum amyloid P (SAP) also occurred. This model allows repeated samples to be obtained from the same animal for the assessment of inflammatory parameters and may be useful for investigating the mechanisms controlling the production of IL-1 during the inflammatory response in vivo.

Animals↗
PubMed1993

Interleukin-1 (IL-1) production in a mouse tissue chamber model of inflammation. II. Identification of (tissue) macrophages as the IL-1 producing cells and the effect of anti-inflammatory drugs.

We have used our newly described mouse tissue chamber model [1], to investigate the process of IL-1 production in more detail. The inflammatory reaction in the tissue surrounding the implanted chambers was investigated histologically and by using the polymerase chain reaction (PCR). The inflammatory response included influx of leucocytes into the granuloma surrounding the tissue chamber, expression of IL-1 beta on macrophages present in the inflamed tissue and an increase in the mRNA coding for IL-1 beta and IL-6 proteins in the granuloma. The effects of three anti-inflammatory or immunosuppressive drugs, prednisolone, indomethacin and cyclosporin A, on IL-1 beta and PGE2 production in zymosan and Bordetella-pertussis-vaccine (BPV)-challenged tissue chambers were also examined. Oral treatment with prednisolone and cyclosporin A of zymosan-challenged animals showed a dose-dependent reduction of IL-1 beta concentrations, but no effect of indomethacin. Both prednisolone and indomethacin dose-dependently reduced PGE2 concentrations to control levels, while cyclosporin A was effective only at the highest dose tested (100 mg/kg/day p.o.). In drug-treated BPV-challenged animals, prednisolone and cyclosporin A also showed a dose-dependent reduction of IL-1 beta, while indomethacin was again ineffective. Prednisolone and indomethacin also dose-dependently reduced the PGE2 concentrations to control levels, whereas cyclosporin A was effective only at the highest dose tested (100 mg/kg/day p.o.). This model will be useful for investigating the mechanisms controlling the production of IL-1 beta from the mRNA level to the secretion of mature biologically active protein [1], and in the search for new drugs which could selectively interfere with this process.

Animals↗
PubMed1993

The role of quality assurance in future midwifery practice.

Recent recommendations have been made which would give midwives a more central role in maternity care and a greater degree of independence than they currently enjoy. This paper argues that midwives' current attitudes to quality assurance are incompatible with this enhanced role. Research conducted in three health districts is described, which explored the perceptions of nurses, midwives and managers towards quality assurance. The findings indicate that quality assurance (in whatever form that concept is operationalized) is a demonstration of accountability. For managers this accountability is primarily for the service as a whole, whilst nurses and midwives view their accountability as being owed to patients/clients. The main methodology which the study identified as being used for monitoring nursing care was the development and auditing of explicit standards. This approach has been actively promoted by the Royal College of Nursing, enabling nurses to regain control of the purely professional aspects of the nursing profession. Midwives in the study districts showed a marked reluctance to adopt such a strategy, taking the view that as independent practitioners consensus standards would be unacceptable. It is argued that this attitude is inconsistent with the basic principle that professionals are accountable for both demonstrating and developing the quality of professional practice. It is further suggested that midwives currently have an opportunity to regain professional control of midwifery practice, which will be lost unless they are prepared to take responsibility for evaluating the standards for which they are accountable.

Attitude of Health Personnel↗
PubMed1993

Risk behaviour, anti-HIV and anti-hepatitis B core prevalence in clinic and non-clinic samples of gay men in England, 1991-1992.

OBJECTIVE: To describe the sexual risk behaviour of and HIV and hepatitis B antibody prevalence in gay men in England. DESIGN: Cross-sectional. RESPONDENTS: Gay men recruited from community settings (bars, clubs, gay organizations) and genito-urinary clinics in London, Manchester, the Midlands and Bristol; men who participated in an earlier study. METHODS: Interview including demographic information, sexual behaviour, partner type and health service use. Subjects donated saliva, which was screened for antibodies to HIV-1 by immunoglobulin G (IgG) antibody capture enzyme-linked immunosorbent assay (GACELISA) and to hepatitis B core (HBc) antigen by IgG antibody capture radioimmunoassay (GACRIA). RESULTS: Ninety-four out of 580 (16.2%) men were HIV-antibody-positive; 6.2% of men aged < or = 25 years were positive versus 19.5% of men aged > or = 26 years. HIV-antibody prevalence was highest in London (21.1%), and twice that previously reported outside London (10.5%). Ninety-four out of 568 (16.5%) men were HBc-antibody-positive; 6.9% of men aged < or = 25 years were positive versus 19.7% of men aged > or = 26 years. Anti-HBc prevalence was highest in London (19.8 versus 12.7% outside London). Manual workers were more likely to be anti-HBc-positive, as were men who reported recent high-risk intercourse. Sexually transmitted diseases associated with frequent partner change (gonorrhoea, non-specific urethritis) were reported. CONCLUSION: The HIV epidemic in gay men in England continues, particularly outside London, where prevalence was double that of previous studies. We found relatively high rates of infection in young men whose main sexual experience has been in a time of unprecedented awareness of AIDS. Our data on hepatitis B suggests that further pro-active immunization programmes are urgently required. These findings add to concerns about provision of interventions targeting gay men.

Adult↗